Imine Nitrogen Atoms Research Articles

A new organometallic palladium(II) compound derived of 2,6-diacetylpyridine mono(thiosemicarbazone): Synthesis, spectroscopic properties and crystal structure of two solvatomorphic forms

Preparation and characterization of a novel 2,6-diacetylpyridine mono(4-methoxyphenyl-thiosemicarbazone), H2L, is described. Treatment of H2L with PdCl2(PPh3)2 gave the neutral mononuclear complex [PdL(PPh3)]. Both compounds have been characterized by elemental analysis and FAB+ spectrometry and by IR and 1H NMR spectroscopy. Recrystallization of [PdL(PPh3)] in DMSO led to the isolation of two solvatomorphic forms of this compound which were studied by X-ray crystallography. In each solvatomorph, the thiosemicarbazone ligand acts as dianionic [CNS] tridentate donor coordinating to the palladium(II) ion in a square planar geometry through the iminic nitrogen atom, the sulfur atom and one ortho carbon atom of the pyridine ring and the fourth site is occupied by P atom from the PPh3 coligand. The overall molecular conformation of the two solvatomorphs is very similar and the largest difference lies in the orientation of the methyl group of the 4-methoxyphenyl substituent with respect to the sulfur atom.

The Preparation and Structure of [(2,4-Dimethyl-8-ethyl-5,8-diazadec-4-ene-2-amine)chlorocopper(II)] Perchlorate

Copper(II) chloride and perchlorate, N,N-diethylethane-1,2-diamine, react in (m)ethanol with acetone and ammonia to form [(2,4-dimethyl-8-ethyl-5,8-diazadec-4-ene-2-amine)chlorocopper(II)] perchlorate, C12H27Cl2CuN3O4, , monoclinic, C2/c, (Hall-C2/c); a, 26.418(1), b, 9.7385(4); c, 14.0993(5) Å; β, 91.134(3)°. This has copper(II) in tetrahedrally distorted square-planar coordination by one primary, one tertiary, and one imine nitrogen atom and the chloride ion.

A New Cyclic Ligand and Complexes of Its Open-Chain Tautomer With Co(III) and Ni(II) Ions: Synthesis, Characterization and Thermal Properties

A new ligand, 2−(p−tolyl)−1,2,3,4−tetrahydroquinazoline−2 −carbaldehyde oxime, was synthesized from a condensation reaction of oxo−p−tolyl−acetaldehyde oxime with 2−aminobenzyl- amine and then amine−imine−oxime complexes of this compound that formed with Co(III) and Ni(II) ions were obtained. All structures were characterized by spectral methods, elemental analysis, magnetic susceptibility, molar conductivity, and thermal analyses. The results that were obtained show that the cyclic ligand, HL, undergoes a ring−opening reaction upon complexation with metal ions. The Co(III) and Ni(II) complexes have a metal−ligand ratio of 1:2 and the imine ligand coordinates through the amine, imine, and oxime groups nitrogen atoms with metal ions.

Synthesis, characterization and biological activity of diorganotin complexes with ONO terdentate Schiff base

Diorganotin(IV) complexes with general formula R2SnL [H2L=(E)-N′-[1-(5-bromo-2-hydroxyphenyl)ethylidene]-3-hydroxy-2-naphthohydrazide (H2L1) and (E)-N′-[1-(5-chloro-2-hydroxyphenyl)ethylidene]-3-hydroxy-2-naphthohydrazide (H2L2); R=Me, Bu, Ph, Cy, Bz, o-ClBz and p-ClBz (1–14)] have been synthesized and characterized by IR, 1H, 13C and 119Sn NMR spectroscopic techniques and single crystal X-ray diffractometry. The structure of the complexes, {[1-(5-bromo-2-oxidophenyl)ethylidene]-3-hydroxy-2-naphthohydrazidato}dimethyltin(IV), 1, {[1-(5-chloro-2-oxidophenyl)ethylidene]-3-hydroxy-2-naphthohydrazidato}dimethyltin(IV), 8 and {[1-(5-chloro-2-oxidophenyl)ethylidene]-3-hydroxy-2-naphthohydrazidato}dicyclohexyltin(IV), 11 reveals a five-coordinated, trigonal–bipyramidal geometry, whereby the trigonal plane of the complexes consists of the imine nitrogen atom and alkyl groups from the diorganotin moieties. The complexes are stabilized by a strong intramolecular hydrogen bonding between N(2) and O(3)–H(3). The Schiff bases and their corresponding diorganotin(IV) complexes have been evaluated against three human carcinoma cell lines, namely HT29 (human colon carcinoma cell line), SKOV-3 (human ovarian cancer cell line) and MCF7 (hormone-dependent breast carcinoma cell line), for their cytotoxic activities. The dimethyltin derivatives and dibutyltin derivatives of the Schiff base ligands display good cytotoxic activities against the tested cell lines.

Palladium(II) Complex of the 5-Hydroxypyridine-2-carbaldehyde N(4)-ethylthiosemicarbazone: Synthesis and Characterization

The novel complex of 5-hydroxypyridine-2-carbaldehyde N(4)-ethylthiosemicarbazone (HPyEt) with plalladium(II) have been prepared and characterized by elemental analysis, IR, 1H-NMR, UV-visible spectroscopy and mass spectrometry (FAB). Coordination of the anionic thiosemicarbazone ligand is via the pyridyl nitrogen, imine nitrogen and thiolato sulfur atoms and the fourth coordination site being occupied by chloride ion in square planar geometry. DOI: http://dx.doi.org/10.3126/jncs.v28i0.8040 Journal of Nepal Chemical Society Vol.28, 2011 Page 34-41 Uploaded date: March 6, 2013

Ethylene and Styrene Carbon Monoxide Copolymerization Catalyzed by Pyrazolyl Palladium(II) Complexes

The pyrazolyl pyridylimine ligands [2-(3,5-dimethylpyrazol-1-yl)ethyl]pyridin-2-ylmethyleneimine (L1) and [2-(3,5-di-tert-butylpyrazol-1-yl)ethyl]pyridin-2-ylmethyleneimine (L2) and pyrazolyl thienylimine ligands [2-(3,5-dimethylpyrazol-1-yl)ethyl]thiophen-2-ylmethyleneimine (L3), [2-(3,5-di-tert-butyl-pyrazol-1-yl)ethyl]thiophen-2-ylmethyleneimine (L4), [2-(3,5-dimethylpyrazol-1-yl)ethyl]-2-bromothiophen-2-ylmethyleneimine (L5), and [2-(3,5-di-tert-butyl-pyrazol-1-yl)ethyl]-2-bromothiophen-2-ylmethyleneimine (L6) were synthesized by condensation of the appropriate pyrazolylamine and the corresponding aldehyde. Reactions of L1–L6 with [PdCl(Me)(cod)] gave the corresponding palladium(II) complexes [PdCl(Me)(L)] (where L = L1 (1a), L2 (2a), L3 (3a), L4 (4a), L5 (5a), L6 (6a)) in very good yields. The pyridylimine ligands L1 and L2 were found to coordinate via the imine and pyridine nitrogen atoms, while the thienylimine ligands L3–L6 coordinate via imine and pyrazolyl nitrogen atoms to the palladium. The ca...

Synthesis , Characterization and Antibacterial Activity of New Cu ( II ) and Zn ( II ) Complexes of Schiff Bases Derived from 9 - H - Fluoren - 9 - One

Five Schiff base ligands bearing a 9-fluorenylidene unit, L1-L5 where (L1= N'-(9H-fluoren-9ylidene)-2-hydroxy-1-naphthohydrazide, L2= N'-(9H-fluoren-9-ylidene)-3-methoxybenzohydrazide, L3= N'-(9H-fluoren-9-ylidene)nicotinohydrazide, L4= N'-(9H-fluoren-9-ylidene) isonicotinohydrazide, and L5=N'-(9H-fluoren-9-ylidene)-2-phenylacetohydrazide) and their [Zn(L)Cl2] and [Cu(L)Cl2] complexes have been synthesized. The characterization and nature of bonding of these complexes were elucidated by elemental analyses, spectral analyses ( 1 H NMR, FTIR), molar conductivity measurements and thermo-gravimetric studies. Analytical and spectral data revealed that L1 coordinates to metal ions by its imine nitrogen atom and the phenolic oxygen atom with a 1:1 stoichiometry. The L2-L5 coordinates to metal ions by their imine nitrogen atom and the carbonyl oxygen atom with the same as L1 stoichiometry. Most of the free ligands and their complexes exhibit antibacterial activities against a number of pathogenic bacteria. The activities of metal complexes are found to be higher than those of the free ligands.

HIGHER-COORDINATE COMPLEXES OF SILICON(IV) WITH N-SALICYLIDENE-2-AMINOPYRIDINE: SYNTHESIS, CHARACTERIZATION, REACTIVITY, AND ANTIBACTERIAL STUDIES

A series of novel higher-coordinate complexes of silicon(IV) X3Si{O-C6H4–2-[CH = N(C5H4N)]}(1–6) with coordination spheres consisting of substituents X = (OEt, Ph, Cl, and NCS) and bidentate Schiff base ligand HO-C6H4–2-[CH = N(C5H4N)] derived from 2-aminopyridine and salicyldehyde have been synthesized and characterized by elemental analyses, infrared spectroscopy, 1H, 13C NMR spectroscopy, and mass spectrometry. The spectral data showed that the Schiff base acted as a monobasic bidentate ligand via imine nitrogen and phenolic oxygen atoms. The thermal stability of complexes (1–6) was studied by thermogravimetric analysis. The antibacterial activities of compounds (1–6) were screened against both Gram-negative bacteria (Escherichia coli and Vibrio cholerae) and Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus). Graphical :

X-ray absorption spectroscopy of nanostructured polyanilines

AbstractIn this paper, X-ray absorption near edge spectroscopy at the nitrogen K edge (N K XANES) data of polyaniline (PANI) and its derivatives were revisited and expanded. The N K XANES spectra of PANI nanocomposites and PANI nanofibers were also investigated. The analysis of N K XANES spectra were done by the deconvolution of bands and the 1s → π* and 1s → σ* transitions were assigned by a correlation with the N K XANES spectra of smaller organic compounds. The “free” forms of PANI were dominated by bands from 397.7 eV to 399.1 eV attributed to imine and radical cation nitrogen atoms, respectively. Nitrogen bonded to phenazine-like rings can also be seen, mainly for PANI prepared at pH higher than 3.0. The spectra of nanocomposites show sharper bands than the “free” polymers as well as new bands at 398.8 eV and 405–406 eV. These new bands were assigned to phenazine-like rings and azo bonds in the structure of the polymers (polyaniline, polybenzidine, and poly(p-phenylediamine)) within the galleries of the montmorillonite clay. PANI nanofibers doped with HCl or HClO4 show bands related to phenazine-like rings and/or dication segments of PANI, indicating that these segments are important in the formation of PANI nanofibers.

The influence of strong and weak hydrogen bonds on the solid state arrangement of hydroxy-containing boron subphthalocyanines

We have investigated the occurrence of hydrogen bonding in boron subphthalocyanine (BsubPc) derivatives by synthesizing a series of four hydroxy-containing BsubPcs and studying their solid state arrangements using X-ray diffraction. The series of derivatives comprises hydroxy-BsubPc (HO-BsubPc) as well as para-, meta-, and ortho-hydroxy-phenoxy-BsubPc (p-, m- and o-HOPhO-BsubPc). Each solid state arrangement demonstrated both strong (O–H⋯N, O–H⋯O) and weak (C–H⋯O, C–H⋯N) hydrogen bonds, with the structure for o-HOPhO-BsubPc including examples of bifurcated hydrogen bonds. Many of the C–H⋯O interactions were found to occur alongside notable perturbations to the expected intra- and intermolecular geometry of BsubPcs, providing structural evidence for the significance of weak C–H⋯O bonds. We observed that the imine nitrogen atom of the BsubPc moiety is a reliable hydrogen bond acceptor, and in most arrangements, the hydroxy moiety participated in hydrogen bonds both as a donor and an acceptor. The presence of hydrogen bonds in addition to other intermolecular interactions (π–π and CH–π, which are common in BsubPc solid state arrangements) facilitates the arrangement of BsubPc into two- and three-dimensional networks of closely associated molecules.

Synthesis, characterization and crystal structure determination of a new vanadium(IV) Schiff base complex (VOL2) and investigation of its catalytic activity in the epoxidation of cyclooctene

The vanadium(IV) Schiff base complex VOL2, L=2-{(E)-[2-chloroethyl)imino]methyl}-6-methoxy phenol, has been synthesized by the reaction of a methanolic solution of VO(acac)2 with a methanolic solution of the Schiff base ligand, and it has been characterized using single-crystal X-ray crystallography, elemental analysis (CHN) and FT-IR spectroscopy. The crystal structure determination of this complex shows a deformed tetragonal pyramidal N2O3 coordination sphere of the vanadium center. The Schiff base ligand acts as a bidentate ligand with the two phenolato oxygen atoms and the two imine nitrogen atoms in trans positions. Non-classical inter- and intra-molecular hydrogen bonds of the type CH⋯O have been found in the structure, the latter connecting the monomeric VOL2 units. The catalytic activity of the VOL2 Schiff base complex in the epoxidation of cyclooctene was investigated using different reaction parameters, such as solvent effect, oxidant, alkene/oxidant ratio and the catalyst amount. The results showed that with a catalytic amount of the VOL2 Schiff base complex and a 1:3 ratio of the cyclooctene/TBHP, the cyclooctene was effectively and selectively converted into the corresponding epoxide with CHCl3 as the solvent.

Novel copper(II) and cobalt(II) complexes with selenium substituted imidazolyl imines. The molecular and crystal structure of [N-(2-(phenylseleno)ethyl)-N-(imidazol-2-ylmethylene)amine]copper(II) dichloride

A series of copper(II) and cobalt(II) complexes with novel selenium containing Schiff base ligands obtained from 2- or 3-aminoalkyl phenyl selenides and imidazole carbaldehydes have been synthesized by the interaction of corresponding organic ligands with MCl2·6H2O (M=Cu, Co). The crystal structure of a copper(II) complex with N-(2-(phenylseleno)ethyl)-N-(imidazolyl-2-ylmethylene)amine has been solved by a single-crystal X-ray diffraction method. The copper(II) ions are coordinated by the imine and imidazole nitrogen atoms of organic ligands and two chloride anions in a distorted square planar geometry. The electrochemical investigations of the synthesized ligands and complexes have been made by cyclic voltammetry method. It is established that the first stage of complexes reduction takes place to metal and the reduced forms of complexes are stable in the solution.

Synthesis and characterization of tin complexes [Sn(L)Hal4] (L = N-alkyl-(pyridin-2-yl)aldimine; Hal = Cl, Br): A structural study

The reactions of the ligands N-methyl-(pyridin-2-yl)aldimine (a), N-ethyl-(pyridin-2-yl)aldimine (b), and N-benzyl-(pyridin-2-yl)aldimine (c) with SnCl4 and SnBr4 led to the formation of compounds [Sn{(C5H4N)HCNMe}Cl4] (1), [Sn{(C5H4N)HCNMe}Br4] (2), [Sn{(C5H4N)HCNEt}Cl4] (3), [Sn{(C5H4N)HCNEt}Br4] (4), [Sn{(C5H4N)HCNBn}Cl4] (5), and [Sn{(C5H4N)HCNBn}Br4] (6) in good yields. All the compounds were characterized by 1H, 13C{1H}, and 119Sn{1H} NMR, vibrational IR-Raman spectroscopy, elemental analyses, and X-ray diffraction analysis. The structural studies confirmed the formation of the respective six-coordinate tin complexes as a result of the chelation of the iminic and pyridinic nitrogen atoms of the ligands towards the tin atom; the Sn–N distances were shortened as the Lewis acid character at the tin atom was increased. In all the molecular structures the tin atom displayed a distorted octahedral local geometry.

Biological activity of Co(III) and Ni(II) complexes of pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone: Synthesis, characterization, crystal structure of Co(III) complex of pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone1

Transition metal complexes formulated as [Co(L)2]ClO4 (I) and [Ni(L)2] · H2O (II), where HL = pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone, have been synthesized. Complex I was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction studies. In complex I, the ligand is N2S tridentate, coordinating to the metal center through pyridine nitrogen, imine nitrogen and sulfur atoms. Hydrogen bonds link the different components to stabilize the crystal structure. Preliminary in vitro screening indicated that the free ligand was active against various bacteria and fungi and all the tested compounds showed significant antitumor activity against K562 leukaemia cell line, and can therefore be candidates for further stages of screening in vitro and/or in vivo.

Syntheses and characterizations of a novel 1,2,3,4-tetrahydroquinazoline and a Co(III) complex

The 2-furan-2-yl-1,2,3,4-tetrahydroquinazoline-2-carbaldehyde oxime (HL) and complex of tridentate ligand containing oxime, imine, and amine donors resulting from reactions with cobalt(II) salt have been synthesized and characterized by spectral methods (FT-IR, NMR, UV-Vis, mass), elemental analysis, magnetic susceptibility, molar conductivity, and thermal analysis (TG, DTA) techniques. The molecular structure of HL was elucidated from single-crystal X-ray diffraction. X-ray crystallographic analysis shows that the molecule crystallizes in the monoclinic system, space group C2/c. In the complex, chloride was not coordinated as confirmed by conductivity measurements. The metal is coordinated to the oxime, imine, and amine nitrogen atoms and decomposes with loss of the organic ligand and halogen to leave metal oxide. The metal to ligand ratio was 1 : 2 by elemental analysis and mass spectrum.

Water Absorbed by Polyaniline Emeraldine Tends to Organize, Forming Nanodrops

Interactions, in terms of both binding energies and microscopic organization, of water molecules absorbed by hydrophilic polyaniline emeraldine base have been investigated using quantum mechanical calculations, molecular dynamics simulation, FTIR spectroscopy, and (1)H NMR. From an enthalpic point of view, water molecules interact more favorably with imine nitrogen atoms than with amine ones, even though the latter are entropically favored with respect to the former because of their two binding sites. Quantum mechanical results show that interaction energies of water molecules reversibly absorbed but organized individually around a binding site range from 3.0 to 6.3 kcal/mol, which is in good agreement with activation energies of 3-5 kcal/mol previously determined by thermodynamic measurements. The irreversible absorption of water to produce C-OH groups in rings of diimine units has been examined considering a three steps process in which water molecules act as both acidic and nucleophilic reagent. Although calculations predict that the whole process is disfavored by 5-8 kcal/mol only, FTIR and (1)H NMR detected the existence of reversibly absorbed water but not of C-OH groups. Both the binding energies and the structural information provided by molecular dynamics simulations have been used to interpret the existence of two types of physisorbed water molecules: (i) those that interact individually with polymer chains and (ii) those immersed in nanodrops that are contained within the polymeric matrix. The binding energies calculated for these two types of water molecules are fully consistent with the thermodynamic activation energies previously reported.

Linking of amino-capped quinonediimines by divalent transition metal ions: Synthesis, characterization, and comparison to electronic structure calculations

Quantum mechanical density functional theory (DFT) calculations are reported for novel, self-assembled transition metal linked dimers of N,N′-bis (3′-carboxy,4′-aminophenyl)-1,4-quinonediimine, with the metals manganese, iron, cobalt, nickel, copper and zinc each in the +2 oxidation state. Infrared spectroscopy detected systematic changes in the carbon–nitrogen double bond involving the imine nitrogen atoms, from 1457cm−1 for manganese complex to 1622cm−1 for the iron complexes. The calculated electronic band gaps of the complexes compare favorably to those for the uncomplexed quinonediimines. The synthesis of the compounds demonstrates a feasible route to the design of a tunable architecture of linear molecular wires derived from properly derivatized quinonediimines.

Coordination and reactivity study of titanium phenoxo complexes containing a bulky bidentate imino-N-heterocyclic carbene ligand

The synthesis and structural characterisation of early transition metal complexes containing the aryl-substituted acyclic imino-N-heterocyclic carbene ligand are reported. X-ray crystallographic studies of titanium phenoxo complexes confirmed that the NHC ligand coordinates through the carbenoid carbon and the imine nitrogen atoms to form an octahedral complex. NMR spectroscopic analyses revealed restricted rotation about the aryl bonds. Attempts to prepare the corresponding titanium imido complex repeatedly led to decomposition products, presumably due to the enhanced reactivity of the imine group resulting in its cleavage from the C^Imine ligand scaffold. The catalytic activities of the phenoxo complexes towards ethylene polymerisation were assessed.

Synthesis, Crystallographic and Spectral Characterization of a Cadmium Chloride Complex Containing a Novel Imidazo[1,5-a]Pyridine Derivative

The reaction between 2-(2-amino-ethylamino)ethanol and pyridine-2-carbaldehyde in a 1 : 3 molar ratio gave 3-(pyridin-2-yl)-1-(pyridin-2-ylmethyl)imidazo[1,5-a]pyridine (PPIP) which was characterized by elemental analysis and spectroscopic methods. The study of CSD-deposited structures revealed that PPIP is a new derivative of imidazo[1,5-a]pyridine. The cadmium chloride complex of this ligand [Cd(PPIP)Cl2][Cd(PPIP)Cl2]ʹ·3H2O (1) was prepared and identified by elemental analysis, FT-IR, Raman and 1H NMR spectroscopy, and single-crystal X-ray diffraction. In the crystal structure of 1, there are two cadmium complexes with slightly different coordination bond lengths and angles. Also water molecules are incorporated in the crystal network. The geometry around the cadmium atom which is coordinated by two pyridine and one imine nitrogen atoms and two chloride ions is distorted square pyramidal. All bond lengths compare well with CSD averages of similar structures. The hydrogen bonds including O-H...Cl and O-H...O present in the crystal structure of 1 are also comparable to those in analogs.

Synthesis, characterization, biological screenings and interaction with calf thymus DNA as well as electrochemical studies of adducts formed by azomethine [2-((3,5-dimethylphenylimino)methyl)phenol] and organotin(IV) chlorides

Novel azomethine adducts of Sn(IV) have been synthesized by the reaction of RnSnCl4−n (n=1–3, R=CH3, n-C4H9, C6H5, C6H11) with 2-((3,5-dimethylphenylimino)methyl)phenol (HL). The products were characterized by elemental analysis, FT-IR, 1H, 13C and 119Sn NMR spectroscopy. Triphenyltin(IV) chloride [2-((3,5-dimethylphenylimino)methyl)phenol] (3) was also characterized by single crystal analysis. Spectroscopic and crystal data suggest that in all the complexes the ligand acts as a monodentate neutral molecule and is coordinated through oxygen to the tin atom forming pentacoordinated tin species. The phenolic hydrogen within the ligand is transferred to the imine nitrogen atom due to the coordination of oxygen with tin after complex formation. The ligand and its complexes have been screened for their biological activities, including DNA interaction, enzymatic, antibacterial, antifungal and cytotoxicity studies. Moreover, the electrochemical behavior of the synthesized compounds was also studied and the results obtained evidenced their irreversible oxidation.